Island



'UNITED STATES PATENT series;

eHAnLEsP. I-IIDDEN, or raovinnnen, nnenn ISLAME, essrsnon 'ro nITncGEN PRODUCTS COMPANY, A conrenerron' or nnonn ISLAND.

FURNACE.

To all whom it may concern:

Be it known that I, CHAnLns P. Himnin, a citizen oi' the' United States, residing at Providence, in the county oi" Providence and State ot Rhode Island, have invented certain new and useful lmprovements in Furnaces, oti? which the 'following is a specification. i

i This invention relates to turnaces :tor the efiectuation of nitrogen fixation processes and the like; and more 'especially concerns a furnace for the Conversion of such inaterials as sodium carbonate into` sodium eyanid; the fixed nitrogen in the latter being preterably obtained :from free or atmospheric nitrogen, during the operation.

In the patent to John Bucher No. ,120,682, dated December 15 19145, there is disciosed process for fixing atmospheric nitrogen in ,the form of the cyanid of an alkali metal, such as sodium; and in certain of its more limited aspects, the herein described turnace may be regarded as an improvement uponthat described by said Bncher in said patent. i i

The presentinvention has for one ot its objects the provision of means for increesing the output from a given turnace; While permitting effective cyanization of the charge.

Another object isto so construct the apparatns as to permit of its being readily assenibled and disassembied. These and other obiects of my invention willbe hereinatter refet-red to and thenovel combinations of means and elements whereby said objects may be attained, will be more particularly.

pointed out in the claims appended heret In the di'awing, whichtorms a part hereot, l have somewhat diagrammatically exemplilied a preferred construction; butas I am aware of various changes and modifications which may be made `herein without departing :ti-om the spiritot my invention, li desire to be limited only by the seope oi said claims, broadiyconsidered in the light of my disclosure.` i 4 Referring to the drawing: Figure l 'is a vertical section ot the :tun nace; the section being taken on the axis ot the retort; and

lg. 2 is a partial detail section taken `on line Ivi- II otllg. 1.

As shown in the drawing, the retort preterably comprises two shells; the outer shell being designated l, and the inner one, 2.

Specificaton of Letters Patent.

caused to impinge against a na Patented Ang. 3, 1920.

i Application filed January 27, 1919. Serial No. 273,456.

` 10 or 12 inches smaller in diameter than section l; so that there is left an annular space between the opposed walls of these sections, 5 or 6 thick, or more, adapted 'for the reception of the charge 4:.

Section 2 is somewhat thimble-shaped and may be formecl oi: iron, but ispreferebly of heat resistant alloy, such as one made of a suitable mixture of nickel, iron and chromium, or the like; and in some cases I also prefer to make the outer cylinder l of i such material.

These concentric shells or cylinders are mounted vertically in a suitable `furnace, which may Conveniently be of the muiiie type. The brick work of the turnace has been designated 5 and comprises a Conduit 6, through which the heating may be introduced, these gases preferebiy being i, and

thence they pass into contact with a sectien Bfio'fthe brick Work, which is so formed as to co-act with the wall 7, to detlect the flames or hot gases more immediately intoend of said retort. Thiis, the lower end of the retort may be heated to a temperature, :tor example, of 1050 C., while the upper end may be heated to 1000 C., or somewhat less. The gases emerging frointhe Conduit (3 pass through the ch amber 9 in which the retort is disposed, and emerge via a conduit 10; whence they pass through a tiue 11.

The lower end of the cooling section 3 is received into a part of the casing lQ for the feed mechanism, which mechanism removes the cyanized and relatively cooled charge from the retort. As this mechanism forms no part of `the present invention, a portion only of the casing tor the same has been shown,

l nto the hopp'er 14 is inserted a casting 16,-provided with a plura lity of ribs 16', which extend ru-chally outward and have their o'uter ejclges shaped to `adapt them for receptien into the hopper 14. The lower ends of theseribs have their eclge's sloped,

as shown, so that the casting 16 -s firfrily supported in and bythe hopper M.

. Upon the interier wall of the casting '16 are a plu-rality of *lugs 17, and the lower eX- tremity of said casting is providedwith an 'interierannu la r flange 17 ,"Wl'1-1Cl1 n 'cross section'iorms a substantial ly hooked shaped element, adap'ted 'or engagement with the -outturned flange 18 at the upper end 'of retert section 2.

The invertedi thimble 2 hence depends frem the' casting LG and in order to prevent :the charge in the furnace from displacing 'the thim'jble out of aXial alinement with the cylinclrical section 1,-in 'the event of 'some irregularity in the feed of the c'harge, flat oval'blocks 19 maybe driven in beneath 'the lugsl'?, so as, in effect, to wedge the u `fiange 18 down against the book-like inte- -rior 'flange at the lower end 'of the cast- 'ing 16! 5 The advantage ofthis Construction resic'les in the fact that these b locks l) may be readilyhnocked ont of place after-the retort hasbeen part'ly'disassembled, in order to sepa` ratevth'e casting 16 from the section 2. If

bolts, or the like were employed to secure these parts together, then, owing to the heat to which they are subjected, -it would at times be found exceec'lingly difficult to remove such bolts. p

v The upper encl of the casting 1'6 is provided with an 'interiorly directed fiange`20,

Whichis prefer'ably annula-rly recessed for V the reeeption of kieselghur or the like, as

'ferred to."

at 21 ;to'prov'ide a seal.

' ;Above the casting '16 is an in verted fun- 'nel-shaped member 22,t*he lower extremity of which is provided with -an outwardly directed flange 22" which is received 'intothe y kieselguh r2 l,}to complete the -seal above re- The weight of the member 22, may 'be sustained in'part by the casting 16; but is pref- `era bly principal ly carried more directly by 'the framework l, through the inftermed iacy of a flanged ring 23, which is'integra lly united to 'them'eniber by ribs 24. These latter are of the same number as ribs 16' and desirably register therewith, so that the briquets fed into the hopper-like space :25, at no time encounter an obstruction to their downward movement. In other words, the space 25 is really an annulus which is (livided into compartments by radially (lirectedpartitions 24, as shown in Fig. 2.

I have described how the cylindrieal section l is exterior'ly heated by combustion gases in the mul'l'le furnace. and shall, now consider the preferred mode of interiorly heating thimble-section -2 of the retort.

A spider 26 is introduced into the casting lG and the extremities of its legs muy rest directly upon the fiange 18 of the thinble 2. This spider is centrally apertured for the reception of a pipe 27, whichdepends 'therethrough and preferably extends down, well. toward 'the bottom of the thiinble. Pipe 27 may be formed of such an alloy as that e above mentioned, or it may be formecl or' used siliea, or the like.

The upper 'end of pipe 27 is enhrged loi' the reception of a pipe 98, -provision being made as by means of an annulnr recess 29', for the insertion of suitable scaling inaterial, such as kieselguhr or the like.

Pipe 28 is Secured to an elbow 29, to the other end of which, preferably through the intermediacy of a reducing 'fiange 30', is connected a short pipe section or nipp'le 30, which extends `'laterally out through the wall of the member 22.

Fue'l gas `may be introdneed into the pipes 28 'and 27 'from a pipe 31, which may be 100 coupled to the nipple 30 by means of a sleeve 32.

To facilitate remeva l of the retort froni the furnace, pipe '31 -may, if desired, be mounted so that it may be swung aside or 105 swiveled out of the way, after which sleeve may be disengaged froni the nipple 30; the casting 33 being pivotally connected -to -the pipe 31 and a lso, desirably, constituting a trap for any tar, or the like, present in the fuel gas.

In *the interier of pi-pes 98 and 27, is a smaller pipe 34, through which air is :ul-

'mitted; this pipe extending up through the elbow 29 and, by suitable conneetions, thence projects laterally through the wall of member 22. It may receive air .froni a pipe 35, to which it maybe coupled by asleeve 36.

The pipe -l may be provided with lterally directed luge 3%', to space it from pipe 27.

The combination of pipes 97 und 34-, forms in efleet an invertec l 'Bn nsen burner, the fiame from which is directed down wardlytoward the bottom of the thimble section 2. To preserve this part of the retort from excessive heating, I prefer to fill the lower extrenity of said section i? with suitable 'lieatn'esistant material %37,180

which maybe introduced in plastic condition and molded nto the' shape shown.

The flames emerging from the lower end 'ot pipe 27, are defiected by the heat-resistant material 37 and thence travel upwardly in contact with the" inner wall of thmble 2, and heat the latter at its lower extremity to approximately 1050 C., the upper end being somewhat less highly heated, in cor respondence withthe mode of heating section 1, above described. i

I have :found it desirable,although by no means essential, to introduce hot nitrogen into the space 38, directly below thimble 2, and this nitrogen. may be introduced via a pipe 39, which extends down through member 22 and casting 1.6, into the thimble, in which latter said pipe is preferably coiled as at 39', for a portion of its length.

,This pipe may be formed of alloy, or it made of iron, it is preferably protected at at least the lower extremity thereof by annuli 4:0 of alundum, or the like, while the coil 39' may be supported upon brackets 4:1, welded to the inner Wall of the thimble.

The lower extremity o'f pipe 39 mayproj ectthrough a small aperture in the bottom of section 2 this aperture being sealed around said pipe, by the material 37 atere- Said. v

The preferred mode of Operating the furnace is as follows: 4 W

The material to be cyanized, preferably in the 'form 'of briquets and comprisinz intimat'elymixed sodium carbonate, finely pulverulent cokeror other suitable carbo'iaceous material,` and` finely divided iron, is charged into the hopper 25 until the annular space between the retort sections 1 and 2, and, of

course, any space therebelow, have been sub.-

-stantially filled The briqueted charge also preferably extends up to the ,top of the ring 23. p i The retort meanwhile, andindeed prefer- .ably previously, has been heated interiorly as .well as exteriorly; the latter by means ot the combustion gases emerging from the conduit G, which traversethe chamberQ and pass thence into the flue 11, as above described; vhile fuel gas is admitted through pipe 31 and pipes 28 and 27 and in the latter smixed with air, under suitable pressure, admitted through pipe 34:. The fuel gas will be, of course, under a pressure corresponding t that of the air, and the gaseous mixture will, by the time :that it is delivered from the end of pipe 27, be highly heated and very effective combustion. can-hence be obtained; whereby to heat the inner retort section orthimble 2 up to the indicated temperatures.

. Nitrogen passingthrough pipe 39 Will, of course, be highly preheated and will emerge i into thespace immediately below the section 2; at which point it will encounter a current of nitrogen ascending from the feed mechanism casing. This latter nitrogenis hot, byreason of its having encountered the descending charge of cyanized briqucts, after the -furnace has been in operation a reasonable time; but it is by no means as highly heated as is the nitrogen which emerges from pine 39. It is, in fact, sufficiently 'cool to chill the fused material in ,the descending briquet mass;this material comprising molten cyanid and sodium carbonate. When briquets containing this molten mixture are th'us eXposed to the nitrogen current at a point where the temperature of the latter is below the eutectic point of the mixed cyanidvand .soda-ash or solium rarbonate, this, mixture solidifies and in so doing, becomes for a time quite adhesive or tacky. r

lili at such time, a portion of the retort wall is in contact with briquets, the cyanid content of which is theret'ore just inthe .act of setting or solidi'fying; such briquets will tend to adhere to the rctort wall with which they are brought into contact and will hence tend to impcde the progress otthe charge through the retort.

It is for this reason that the inner section or thimble 2, has the bottom thereof so shaped asto, in effect, abruptly removeits wall from possible contact with the descending charge, at a point a short distance above where the charge begins to set and hence to l'iecome tacky, as above described.

.ln other words, the descending briquets,

while r ing down between the cylindrical Walls oi retort sections 1 and 2, and while exposed to the intense heat to which they are subjectechare moreor less plastic and as the cyanid is formed therein'according to the equation: i

Na CO --N fl-C-l-lronz i NaCN--BCO ilron it normally s is molten and atter a fashion acts as a lubricant. After a given portion of the charge becomes cyanized, however, and descends below the level of the fioor of the furnace, it begins to cool and by the time that it reaches the level of the 'bottom of the thimble 2, it is very ncarly ready to set or harden, ii it is located in the vicinity of said thimble. It, however, does not set until t has cleared thev lower end of the section 2 and hence the mass of brquets will normally i S o 1 cyonicl-forming reaetion.

If eyanicl is formeclto `any eonsi'clerab'le 'geh 'which also fiows up trointhe `fee d mechanisni cesi'ng alongside 'of the 'Inner Wall 'of the cooling section 3, is 'not materially adnixed With 'hot nitrogen from the pipe 39; 'andhenc'e'the oiiter'briquets, or those more 'nearly m'et to the' section 1, Wil l'tendto setsooner than those in 'the interier of the ehrge; Thecool'ing section 3 is'offset 'froni 'fthebottoni of the section l, "to Permit these -briquets,-thus 'in "contact With the section *1 'as 'they 'a roach 'the lower endet the lat- "ter, to become teck'y and set, 'out of "contact im-i into 'the feed mechanisni casing; While fresh material, 'inthe' iorm 'of uncya'nized b riquet's maybe loaded into 'the Compartneecle; V w ,i

The 'advantage' of thu's introclueng hot nitrogen in the man-ner described, via pipe mente& space 25, from time to time, es

'39,01 its equivalent, is that while 'the nitrogen,'-as whole, is not supplied at such a hgh temperature es to prevent proper setting of the brquet whch Would obvi- ;onsly interfere With the' operation of the furnace; neverthelesg this 'supplemental stream ;of highly he'te'cl nitrogen, raises the [temperature of the entire flow of nitrogen,

just as 'it is about to `enter the he at zone of the'annular charge, and 'thereby voi's the extentfin the upper part of the, retort, there is a tendency for much of this cyanid to Volatilize and pass upwardly along with the ascending nitrogen and cei bon ni'onoxid,

'until it 'reaches a point at or nearthe top of the heat zone', 'where its temperature is low erecl "snfliciently to permit of the clestruction of saicl'cyanicl With reformation of soclium carbonate This is so because, at a temperature for example 'of 1000 C., even 15% of earbon mo'noxicl in'the nitrogen eurrent, will prerti'cally prohibit cyani formation; while a greate'r contentof CO, at thisteinperature,

"even tencls to reverse the reaction and hence to Convert 'the eyanid back to sotlium carbo- .nate. y

The content. of cerbon inonoxicl 'tends to steclily-increase in the ascending gaseous current; because carbon InonoXid is liberatecl "wherever the cyanid is fo'rne d, and hence, by reason of the presence of a relatively high content of 'earbon monoxid in the upper end oi? the heat zone, ii" the tenipereture be kept down, to, let us say, 1000 C., there is then little tendency 'for cyanid to form in said upper end.

If cy'anicl is not formed at this point, then'tl iebriquets will elescend through this portion of the furnace With maintenance of Substantially their entire content of socliun carbonate and es the lower end oi' the fur- -nace is most highly heated, and ae. also,

there is a strong incomingcurrent of pure nitrogen, and since, further, this incoming Current, by reason of the added Illt'Of'Cll 'supplied by pipe 39, is alnost up to cyanidforining tentperz'ture,-there is a Very strong cyanid forining reaction eli'ected in the lower quarter of the heat zone.

This cyenid, after having thus eopiously fermed, does not have suilicie'nt tinie to (listil off to any great extent, before it passcs down into the 'cooling section oi" the turnece in which, 'oi' course, it is pronptly rhilleal and ca'n no longer be lost by distillaiion.

On xnfount of diiliculties in connection with the feed niechanisn, especially uhen using' :in 'exterior shell 'of large diameter, it is highly des' "able to eonstr'ct the (louble- `'Walled retort in such fashion that the inuei' 'Section o'r shell thereol depemls into the outer section; While the means :tor supplying heat to said interior section, prei'erably similarly (lepends or extends into the space i xithin said inner shell, substantially :s

' shown.

' By thns using an exterior shell ot large diameter and providing therein a thinble or its e iuivalcnt, capable of eo-acting' there- With to afiord an annular space', the thickness 'of which is not eXcessiVe,-it is possible to' obtain :in output `froni :t single furnace, far in 'excess of thot possible n here a.

*simple pipe-like retort is employed; since,

obviously, the cross-sectional area of the anf'nular charge-receiving space nmy be made many times that of the correspondng area of a simple pipe ot a diameter in any Way well adapted to the process.

Not only IS the output increase l thus ina- ,teriztlly by the disposition of the eharze in the form of a hollow column of large dianeter; but, further, the thickness of' this vol,-

unrn, ineesured radially, may be such as to perniit of a 'rapid heating of the briquets most i'eni'ote 'roin the sources of hezit. To be able thus .promptly to elei'ate to reac- 'tion temperature, substantially all, part s of the charge passing through that part oi the 'heatzone ot the retort, Where it is desired that the cyanid-fornnng reaction shall oecur, greatly favors the obtaininent of a higher percentage yield of cyanid in the product, on account of the reduction of distilletion of eyanid in the heat zone, .in the 'manner above described.

'It Will hence be seen that there is a peculiar inter-action between the various` eleheatin ability.

`Having thus describedmy inventon, what Iclaim ist' 1. A furnace for fixing nitrogen which comprises two concentrically disposed retort sections, one within theother, the common axis of said sections being substantially vertical, means to hoat the'exterior section, auxiliary means to heat theinterior section', means to receive material which descends through the annular space between said sections, said material having theforn of a hollow column and said receiving means having provisionsfor cooling said column both interiorly and` exteriorlywhile preventing adhesion of the charge to any part of the retort during the cooling operation,

said cooling provisions includingmeans to direct a relatively cool stream of nitrogen into contact with the lower end ot said column.

2. A furnace for fiXing nitrogen WlllCll comprises two substantially vertical retort sections, one within the other, mciiansto heat the exterlor sectlon, auxhary means to heat the interiorsection, means to receive 'mater al which descends through the annnlar space between said sections, said material having the form of a hollow column and said receiving means having provisions 'for cooling said columnbothinteriorly and eX- teriorly while i preventing adhesion t of the charge to 'any part of the `retort during the cooling operation, said cooling provisions including means to direct' a `relatively cool stream of nitrogen into contact with the lower end of said column.

3:1\ furnaceffor fixing nitrogen which comprises two snbstantially'vertical retort sections, one within the .other,'means toheat the exterior section, auxiliary means to heat the interior section, 'means to receive material which descends through the annular spam between said sections, said material having the form of a hollow column and said receiving meanshaving provisions for cooling said column both interiorly and eX- teriorly while preventing adhesion of the chargeto any part of the retort during the cooling operation, 'said cooling provisions including means to direct a relatively cool stream of nitrogen into contact with the lower end of said column, and means snpplemental to the heating means aforesaid, for raising the temperature of the nitrogen, as a whole, just prior to its admission to the heat zone of said 'urnace.

et. A 'l'urnace tor lixing nitrogen which comprises a retort which includes a cylindrical exterior section and a thimble in the interior of said section, said thimble being substantially co-aXially located in said exterior section, means to heat said thimble interiorly and said section exteriorly, means to supply free nitrogen to the heated chargereceiving space between said thimble and section, and cooling means to receive said charge after treatment thereof in said space.

5. A furnace :tor xing nitrogen which comprises a retort, the charge-receiving portion of which is substantially annular in cross section said furnace including means to cool the charge emerging therefrom and provisions for el'ecting a vigorous nitrogenixing reaction in said retort only 'at the end oi'` the ,latter which s LClJLCBlli) said coohng means.

6. A furnace 'or fixing nitrogen which comprises a vertical retort, the charge-receiving portion of which is substantially annular in cross section, said furnaceincluding means to cool'the charge emerging therefrom and provisions 'or etl'ecting a vigorous nitrogen-fixing reaction in said retort only at the end of the latter which is adjacent said cooling means. i

7. A furnace `for fixing nitrogen which c'onprises a retort, the charge-receiving portion of which is substantially annular in cross section, said retort including'an exterior shell and a thimble substantially coaxially located within said shell, said furnace having means to heat one end of said iell to a higher temperature than the other, means to heat said thimble interiorly thereof, said thimble heating means having pro'- visions for heating most highly the end ot said thimble which is adjacent the' most highly heated end of said shell.

thimble heating means having provisions 'or heating most highly the lower end o' said thimble, and provisions for cooling the charge substantially directly' after said charge' has been most highly heated in the space between said heated lower ends.

9. A `furnace 'for Xing nitrogen which comprises a retort, the charge-receiving portion of which is substantially annular in terior retort section, means to introduce the charge to be treated in said 'urnace, into the upper portion of the space between said sections, means to heat said eXterior section exteriorly and said interior section interiorly, to supply heat to said space both from within and without the same, provisions to cool the charge upon its emergence from said heated space, and provsions to prevent adhesion of said charge to either of said retort sections while said charge is being cooled. i

18. A continuously feeding furnace for fixing free nitrogen in the form of an alkali metal `cyand, which comprises a retort through which the charge to be cyanized continuously moves, means to heat said retort to 'establish a cyanizing Zone theren, means to supply relatively cool ntrogen to the cyanized charge as the latter moves out of said zone, to solidify the cyand in said charge, means to supply highly heated nitrogen to said zone, for admixture with said relatively cool nitrogen, and means to ,pre-

vent adhesion of said cyanid to said retort, while said cyanid is solidifying.

19. A furnace having a double-walked retort, the space between the double walls of which holds the charge to be treated, means to direct a stream 'of highly heated gas against the exterio' wall of said retort, and means to direct a stream of highly'heated gas against the interior wall of said retort.

20. A furnace having a double-walled vertical retort, the space between the double walls of which holds the charge to be treated, means to heat the eXterior wall, whereby to exterorly heat the charge in .said space, and means, extending into the space within the inner of said walls, for heating said inner wall whereby to heat said charge interiorly thereof.

In testimony whereof I have afiiXed my signature, in the presence oftwo witnesses CHARLES P. HIDDEN. witnesses:

HowAm) F. HYLAND, Room: N. LOBDELL. 

